Radio Frequencies 101: How Wireless Communication Actually Works

We use radio frequencies basically all day, every day, whether we realize it or not.

Your phone uses them. Wi-Fi uses them. Bluetooth uses them. GPS uses them. Walkie-talkies use them. Garage door openers use them. Satellites use them.

They're all using the same basic thing: radio waves.

The interesting part is that they use different parts of the radio spectrum, and those differences have a huge impact on what each technology can actually do.

So let's break it down without turning this into an electrical engineering class.

First, What Is a Radio Frequency?

Radio waves are a form of electromagnetic energy traveling through space.

Frequency describes how many times that wave cycles every second.

One cycle per second is called one hertz, or Hz.

From there: 1 kHz = 1,000 Hz. 1 MHz = 1,000,000 Hz. 1 GHz = 1,000,000,000 Hz.

So when someone says a radio operates at 915 MHz, they're talking about a radio wave cycling approximately 915 million times per second.

The important thing isn't memorizing that number.

It's understanding that different frequencies behave differently.

Frequency Is a Tradeoff

As a general rule, lower frequencies have longer wavelengths and tend to be useful when you want signals to travel farther or interact more favorably with obstacles.

Higher frequencies have shorter wavelengths and can support applications requiring much higher data rates, but they often face different propagation limitations.

That's why there isn't one "best" radio frequency.

It depends entirely on what you're trying to accomplish.

Think about the difference between streaming a 4K movie and sending someone your GPS coordinates.

One requires an enormous amount of data.

The other requires almost nothing.

Those shouldn't necessarily use the same communication technology.

So What Uses What?

Here's where this starts becoming familiar.

AM Radio

AM broadcast radio in the U.S. operates roughly around 530–1700 kHz.

Those are relatively low frequencies with long wavelengths. Under the right conditions, AM signals can travel very long distances, especially at night.

FM Radio

FM broadcast radio operates around 88–108 MHz.

Higher frequency than AM, different propagation characteristics, and much more bandwidth available for higher-fidelity audio.

Two-Way Radios

Different two-way radio services occupy different parts of the spectrum.

GMRS, for example, operates around 462 and 467 MHz.

You'll also hear people talk about VHF and UHF radios. Those frequency ranges have different characteristics that make them useful for different environments and applications.

GPS

GPS is up around 1.2–1.6 GHz, depending on the particular GPS signal.

And here's an important distinction: your GPS receiver isn't talking to the satellites like you're making a phone call.

The satellites transmit extremely precise signals, and your device listens to multiple satellites and uses those signals to determine where it is.

Cellular

Cellular gets considerably more complicated because modern cellular networks use numerous frequency bands.

Depending on the carrier, technology and location, your phone might communicate using frequencies ranging from hundreds of MHz into several GHz.

Lower cellular bands can provide broader coverage and better building penetration, while higher-frequency bands can provide tremendous capacity and speed over shorter distances.

Wi-Fi

The Wi-Fi you're familiar with commonly operates around: 2.4 GHz, 5 GHz, 6 GHz.

Wi-Fi can move an incredible amount of data.

That's why you can stream movies, download huge files and make video calls over it.

But tremendous data capacity isn't always what we need.

And that brings us to LoRa.

LoRa Takes a Different Approach

LoRa stands for Long Range.

Instead of trying to move massive amounts of information extremely quickly, LoRa is designed around sending relatively small amounts of data efficiently over potentially long distances while using very little power.

In the United States, LoRa systems commonly operate in the 902–928 MHz ISM band, often casually referred to as 915 MHz LoRa.

And that puts it in an interesting place.

It's dramatically lower frequency than Wi-Fi, but still high enough that practical antennas and compact devices are possible.

More importantly, the radio technology itself is designed specifically around long-range, low-power communication.

We're trading bandwidth for range and efficiency.

You're not streaming Netflix over LoRa.

But that's not what we're trying to do.

If I need to send: "I'm here." Or a GPS coordinate. Or a short message. Or an SOS.

I don't need the bandwidth required to stream a movie.

I need the message to get there.

Frequency Isn't the Whole Story

This is one misconception worth clearing up.

Frequency alone does not determine range.

Transmit power matters. Antenna design matters. Antenna height matters. Terrain matters. Buildings matter. Vegetation matters. Interference matters. Receiver sensitivity matters. And the modulation technology being used matters.

Two devices operating around the same frequency can have dramatically different performance depending on how the entire radio system is designed.

That's one reason LoRa is interesting. It isn't simply "a 915 MHz radio." The way LoRa encodes and receives information is a major part of what allows it to detect signals at very low signal levels.

Why We're Using LoRa

This is where all of this comes back to Alias.

We're building Rogue around a very different goal than the companies building smartphones.

A smartphone needs enough bandwidth for YouTube, FaceTime, TikTok, web browsing, cloud services and everything else we've come to expect.

Rogue doesn't need to do that.

We're interested in private, resilient communication between devices without requiring a cellular carrier or internet connection.

For that job, we're much more interested in range, power efficiency and reliability than being able to download a 4K movie in ten seconds.

That's why LoRa makes sense.

And when you combine that radio technology with the mesh networking we discussed previously, things get even more interesting.

Individual devices can communicate locally, and additional nodes and repeaters can potentially extend the network farther.

No technology eliminates the laws of physics.

But if you understand the tradeoffs, you can choose the right radio technology for the job.

And that's really the point.

There isn't one perfect frequency. There's the right tool for what you're trying to accomplish.